The present invention relates to electronic throttle control (ETC), and more particularly to an idle area request security control for ETC.
Historically, a throttle of an engine has been mechanically manipulated by a throttle cable, which interconnects the throttle and an accelerator pedal. As the accelerator pedal is depressed, the cable opens the throttle and increases engine torque output. More recently, the mechanical cable system has been replaced by an electronic throttle control (ETC) system. The ETC system includes electronic control modules, sensors and actuators and is also referred to as xe2x80x98Fly-by-Wirexe2x80x99.
There are several advantages in implementing an ETC over a conventional throttle cable. The use of the ETC system ensures that the engine receives the correct amount of throttle opening for any given situation. The optimization of air flow also ensures that exhaust emissions are kept to an absolute minimum and drivability is maintained. Coupling the electronic throttle actuation to adaptive cruise control, traction control, idle speed control and vehicle stability control systems also provides finer control. Other advantages include eliminating mechanical components of the throttle cable. This reduces the number of moving parts (and associated wear) and minimizes adjustment and maintenance. Further, increased control accuracy improves vehicle drivability, which in turn provides better response and fuel economy.
Although the ETC system includes these advantages, further development of the ETC system and control logic for controlling the ETC system is required. This is particularly true for controlling the ETC system at higher engine speeds.
Accordingly, the present invention provides an electronic throttle control (ETC) system to control an idle speed of an engine. The ETC system includes an accessory that increases a load on the engine and a controller that generates an idle request signal based on the increased load. The controller compares the idle request signal to an idle maximum signal and sets an idle command signal equal to the idle request signal if the idle request signal is less than the idle maximum signal. The controller determines the idle command signal based on the idle request signal, a previous idle command signal and the idle maximum increase signal if the idle request signal is greater than the idle maximum signal.
In one feature, the controller sets the idle maximum increase signal equal to an idle speed increase signal.
In another feature, the controller sets the idle command signal equal to a minimum of the idle request signal and a maximum between said idle maximum signal and a sum of the previous idle command signal and the idle maximum increase signal.
In still another feature, the controller compares the idle command signal to an idle brake maximum signal. The controller sets the idle command signal equal to the idle brake maximum signal if the idle command signal is greater than the idle brake maximum signal.
In yet another feature, the controller operates the engine based on the idle command signal.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.